import io.reactivex.Observable;

public class C28 {
    public static void main(String[] args) {
        Observable<String> items = Observable.just("Alpha", "Beta", "Gamma", "Delta", "Epsilon");
        items.filter(s -> s.startsWith("Z"))
             .defaultIfEmpty("None")
             .subscribe(System.out::println);
    }

}
//EOP
